While Yellowstone National Park lies over 1,100 kilometers from the site of the Landers earthquake, the California jolt nonetheless altered geyser eruptions in the park, according to Roderick A. Hutchinson of the National Park Service. Hutchinson made this discovery only because he had fortuitously installed a portable seismometer near the Echinus geyser two days before the earthquake last June.

The prequake record from Echinus shows that the geyser erupted quite regularly, every 56 minutes on average. But immediately after the Landers jolt, that regularity stopped and the geyser erupted erratically over a period of 34 hours. Hutchinson has seen other earthquakes trigger changes in Yellowstone geysers, but the Landers quake was the most distant one to have an effect. He plans to search for similar changes in the eruption records of the Old Faithful geyser, where a permanent infrared sensor monitors eruption frequency

Several hours after the Landers quake, a swarm of small earthquakes began underneath Yellowstone. The California jolt triggered many swarms at other distant sites around the western United States (SN: 8/1/92, p. 72), and seismologists are now trying to understand how the quake could set off such activity at so great a distance.

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